Field of the Invention
The present invention relates to the development of control units as they are used, e.g., in the automotive industry or in the aviation industry for controlling technical systems such as, e.g., engines or brakes. The present invention relates in particular to test devices used in the control unit development process.
Description of the Background Art
The development of control units has become a highly complex process. Thus, new control units or new control functions are to be tested as early as possible in the development process in order to check the general functionality and to set the direction of further development. It is important toward the end of the development process to test the already far developed control unit as comprehensively as possible in order to make the necessary modifications based on the test results before the control unit is placed in use or goes into mass production and functions as desired under all circumstances in later operation.
The methods of hardware-in-the-loop simulation (HIL simulation) and rapid control prototyping (RCP) are known for testing control units. In the HIL simulation, an electronic control unit is connected to a test device (HIL simulator) in which, for example, a software model of the system to be controlled or regulated by the control unit is executed. The software model is also called an environmental model. The test device therefore simulates the physical environment of the later use for the control unit. In RCP, in contrast, a software model of a control unit to be developed or improved is executed in the test device. In the case of RCP, a technical system connected externally to the test device is then controlled or regulated by means of the model executed in the test device via the test device.
The testing of a (mass-produced) control unit employed in the end product is the endpoint of multiple preceding development steps of closed-loop or open-loop control to be implemented in the control unit, whereby these development steps are usually described with the so-called V-model or V-cycle as well. Controller development, essential for the function of many technical systems, starts off with the mathematical modeling of the control algorithm on a computer with a mathematical and graphical modeling environment, whereby the controller should be considered part of the control unit. In addition, the environment of the control unit is also modeled mathematically, because the interaction of the controller on the control unit with the process to be controlled is of interest. In these functional mathematical considerations, a simulation in real time is generally not necessary (offline simulation).
In the next step, the previously developed control algorithm is transferred by rapid control prototyping to a powerful hardware unit that is usually real-time-capable and is connected to the actual physical process by suitable I/O interfaces, therefore, for example, to a motor vehicle engine. This real-time-capable hardware has nothing to do with the mass-produced control unit to be used later. At issue here is proof of the basic functionality in practice of the previously developed control.
In another step, as part of automatic production code generation, the control is implemented in the target processor likely to actually be used later in the mass-produced control unit. Accordingly, in this step, the target hardware approximates the mass-produced control unit, but is not identical to the mass-produced control unit.
In another step, the mass-produced control unit, which normally does not exist until a later development stage, is tested as part of a hardware-in-the-loop test (HIL). The (mass-produced) control unit, physically present in this step, is connected here by its physical control unit interface to a powerful simulation computer, often simply called a simulator. The simulator simulates the required variables of the real control unit to be tested and exchanges input and output variables with the control unit. The pins of the physical control unit interface of the control unit are connected to the simulator by a cable harness. In this way, it is possible to simulate in the simulation environment all required variables, for example, of a motor vehicle engine, if applicable the entire motor vehicle with engine, drivetrain, chassis, and road test, and to test the behavior of the control unit in interaction with the simulation environment in a risk-free manner.
Configuration systems with configuration diagrams are often used for configuring test devices, such as, for example, HIL or RCP systems. These configuration systems can be, e.g., graphical programming environments such as the software environments LabView® from National Instruments® or Simulink® from The Mathworks®.
The known configuration systems or configuration diagrams have the disadvantage that the configuration of the test device hardware properties is time-consuming and laborious.